1. Field of the Invention
The present invention is directed to an interface device and process for controlling a fuel cell and a device powered by the fuel cell. Moreover, the device communicates with both the fuel cell and the powered device.
2. Discussion of Background Information
An electrochemical fuel cell (FC) is a device that converts the energy of a chemical reaction into electricity. Although fuel cells are increasingly gaining acceptance as electrical power sources, there are technical difficulties that prevent the widespread use of fuel cells in many applications, especially mobile and portable applications. In operation, several problems have been observed, including performance degradation in long term low load condition, fuel cell heating occurring as a result of power dissipation on the fuel cell inner impedance, low fuel cell voltage, which is usually is the range of 0.3V-1, decomposing of fuel and electrodes in high ambient temperature, decreasing of fuel cell capacity and energy as a result of low ambient working temperature, and inability of fuel cell to provide full power as a result of low oxygen concentration on the FC cathode. Further, no communication between the FC and the powered device, such that the fuel cell is unaware of the powered device's requirements and vice versa, and changes in the load reduce efficiency are also observed problems in the known art.
Known fuel cells are not capable of being operated under different load conditions without shortened life or of being operated with maximum efficiency. Thus, it would be advantageous to enlarge fuel cell efficiency.
To operate known fuel cells under load, it is generally necessary to the heat the fuel cell, which requires an additional expenditure of energy. Also, when known fuel cells are operated under low ambient working temperature, fuel cell capacity and energy are undesirably decreased.
Another drawback of known fuel cells is that when operated under low oxygen concentration on the fuel cell cathode, the fuel cell is unable to provide power.
Further, while there is potential for using fuel cells as the power source in portable devices, e.g., electronic devices such as cellular telephones, cameras, portable computers, PDAs, audio devices, video devices, medical devices, etc., known fuel cells are not generally able to provide power in a form of higher, regulated and changeable output voltage that is necessary for most portable devices. Moreover, known interfaces do not provide adequate communication between the fuel cell and the portable device and/or between the fuel cell and a host computer.
A further drawback of known fuel cells is that, in high ambient temperature, the undesirable decomposition of fuel and electrodes occurs.